Buggy code:
public void destroy ( ) { } public void doFilter ( ServletRequest request , ServletResponse response , FilterChain chain ) throws IOException , ServletException { if ( ( abortErrorMessage ) != null ) { ( ( HttpServletResponse ) ( response ) ) . sendError ( 500 , abortErrorMessage ) ; return ; } if ( request instanceof HttpServletRequest ) { HttpServletRequest req = ( ( HttpServletRequest ) ( request ) ) ; HttpServletResponse resp = ( ( HttpServletResponse ) ( response ) ) ; SolrRequestHandler handler = null ; SolrQueryRequest solrReq = null ; try { String path = req . getServletPath ( ) ; if ( ( req . getPathInfo ( ) ) != null ) { path += req . getPathInfo ( ) ; } if ( ( ( pathPrefix ) != null ) && ( path . startsWith ( pathPrefix ) ) ) { path = path . substring ( pathPrefix . length ( ) ) ; } int idx = path . indexOf ( ':' ) ; if ( idx > 0 ) { path = path . substring ( 0 , idx ) ; } final SolrCore core ; if ( ( ( multicore ) != null ) && ( multicore . isEnabled ( ) ) ) { if ( path . equals ( multicore . getAdminPath ( ) ) ) { handler = multicore . getMultiCoreHandler ( ) ; core = multicore . getAdminCore ( ) ; if ( core == null ) { throw new RuntimeException ( "Can<seq2seq4repair_space>not<seq2seq4repair_space>find<seq2seq4repair_space>a<seq2seq4repair_space>valid<seq2seq4repair_space>core<seq2seq4repair_space>for<seq2seq4repair_space>the<seq2seq4repair_space>multicore<seq2seq4repair_space>admin<seq2seq4repair_space>handler" ) ; } } else { idx = path . indexOf ( "//" , 1 ) ; if ( idx > 1 ) { String corename = path . substring ( 1 , idx ) ; path = path . substring ( idx ) ; core = multicore . getCore ( corename ) ; } else { core = null ; } } } else { core = singlecore ; } if ( core != null ) { final SolrConfig config = core . getSolrConfig ( ) ; SolrRequestParsers parser = null ; parser = parsers . get ( core ) ; if ( parser == null ) { parser = new SolrRequestParsers ( config ) ; parsers . put ( core , parser ) ; } if ( ( handler == null ) && ( ( path . length ( ) ) > 1 ) ) { handler = core . getRequestHandler ( path ) ; if ( ( handler == null ) && ( parser . isHandleSelect ( ) ) ) { if ( ( "//select" . equals ( path ) ) || ( "//select//" . equals ( path ) ) ) { solrReq = parser . parse ( core , path , req ) ; String qt = solrReq . getParams ( ) . get ( QT ) ; if ( ( qt != null ) && ( qt . startsWith ( "//" ) ) ) { throw new org . apache . solr . common . SolrException ( ErrorCode . BAD_REQUEST , ( "Invalid<seq2seq4repair_space>query<seq2seq4repair_space>type.<seq2seq4repair_space>Do<seq2seq4repair_space>not<seq2seq4repair_space>use<seq2seq4repair_space>//select<seq2seq4repair_space>to<seq2seq4repair_space>access:<seq2seq4repair_space>" + qt ) ) ; } handler = core . getRequestHandler ( qt ) ; if ( handler == null ) { throw new org . apache . solr . common . SolrException ( ErrorCode . BAD_REQUEST , ( "unknown<seq2seq4repair_space>handler:<seq2seq4repair_space>" + qt ) ) ; } } } } if ( handler != null ) { if ( solrReq == null ) { solrReq = parser . parse ( core , path , req ) ; } final Method reqMethod = Method . getMethod ( req . getMethod ( ) ) ; if ( ( Method . POST ) != reqMethod ) { HttpCacheHeaderUtil . setCacheControlHeader ( config , resp ) ; } if ( ( config . getHttpCachingConfig ( ) . isNever304 ( ) ) || ( ! ( HttpCacheHeaderUtil . doCacheHeaderValidation ( solrReq , req , resp ) ) ) ) { SolrQueryResponse solrRsp = new SolrQueryResponse ( ) ; this . execute ( req , handler , solrReq , solrRsp ) ; if ( ( solrRsp . getException ( ) ) != null ) { sendError ( ( ( HttpServletResponse ) ( response ) ) , solrRsp . getException ( ) ) ; } else { QueryResponseWriter responseWriter = core . getQueryResponseWriter ( solrReq ) ; response . setContentType ( responseWriter . getContentType ( solrReq , solrRsp ) ) ; if ( ( Method . HEAD ) != ( Method . getMethod ( req . getMethod ( ) ) ) ) { if ( responseWriter instanceof BinaryQueryResponseWriter ) { BinaryQueryResponseWriter binWriter = ( ( BinaryQueryResponseWriter ) ( responseWriter ) ) ; binWriter . write ( response . getOutputStream ( ) , solrReq , solrRsp ) ; } else { PrintWriter out = response . getWriter ( ) ; responseWriter . write ( out , solrReq , solrRsp ) ; } } } } return ; } else { req . setAttribute ( "org.apache.solr.SolrCore" , core ) ; if ( ( ( singlecore ) == null ) && ( path . startsWith ( "//admin" ) ) ) { <START_BUG> req . getRequestDispatcher ( path ) . forward ( request , response ) ; <END_BUG> return ; } } } log . fine ( ( ( "no<seq2seq4repair_space>handler<seq2seq4repair_space>or<seq2seq4repair_space>core<seq2seq4repair_space>retrieved<seq2seq4repair_space>for<seq2seq4repair_space>" + path ) + ",<seq2seq4repair_space>follow<seq2seq4repair_space>through..." ) ) ; } catch ( Throwable ex ) { sendError ( ( ( HttpServletResponse ) ( response ) ) , ex ) ; return ; } finally { if ( solrReq != null ) { solrReq . close ( ) ; } } } chain . doFilter ( request , response ) ; } protected void execute ( HttpServletRequest req , SolrRequestHandler handler , SolrQueryRequest sreq , SolrQueryResponse rsp ) { } protected void sendError ( HttpServletResponse res , Throwable ex ) throws IOException { } public void setPathPrefix ( String pathPrefix ) { } public String getPathPrefix ( ) { } }

Fix:
req . getRequestDispatcher ( ( ( pathPrefix ) == null ? path : ( pathPrefix ) + path ) ) . forward ( request , response ) ;